Understanding mechanisms of asphaltene adsorption from organic solvent on mica

The adsorption process of asphaltene onto molecularly smooth mica surfaces from toluene solutions of various concentrations (0.01-1 wt %) was studied using a surface forces apparatus (SFA). Adsorption of asphaltenes onto mica was found to be highly dependent on adsorption time and asphaltene concentration of the solution. The adsorption of asphaltenes led to an attractive bridging force between the mica surfaces in asphaltene solution. The adsorption process was identified as being controlled by the diffusion of asphaltenes from the bulk solution to the mica surface with a diffusion coefficient on the order of 10-10 m2/s at room temperature, depending on the asphaltene bulk concentration. This diffusion coefficient corresponds to a hydrodynamic molecular radius of approximately 0.5 nm, indicating that asphaltene diffuses to mica surfaces as individual molecules at very low concentration (e.g., 0.01 wt %). Atomic force microscopy images of the adsorbed asphaltenes on mica support the results of the SFA force measurements. The results from the SFA force measurements provide valuable insights into the molecular interactions (e.g., steric repulsion and bridging attraction as a function of distance) of asphaltenes in organic media and hence their roles in crude oil and bitumen production

Dosimetric evaluation and radioimmunotherapy of anti-tumour multivalent Fab́ fragments

We have been investigating the use of cross-linked divalent (DFM) and trivalent (TFM) versions of the anti-carcinoembryonic antigen (CEA) monoclonal antibody A5B7 as possible alternatives to the parent forms (IgG and F(ab́)2) which have been used previously in clinical radioimmunotherapy (RIT) studies in colorectal carcinoma. Comparative biodistribution studies of similar sized DFM and F(ab́)2 and TFM and IgG, radiolabelled with both 131I and 90Y have been described previously using the human colorectal tumour LS174T nude mouse xenograft model (Casey et al (1996) Br J Cancer 74: 1397–1405). In this study quantitative estimates of radiation distribution and RIT in the xenograft model provided more insight into selecting the most suitable combination for future RIT. Radiation doses were significantly higher in all tissues when antibodies were labelled with 90Y. Major contributing organs were the kidneys, liver and spleen. The extremely high absorbed dose to the kidneys on injection of 90Y-labelled DFM and F(ab́)2 as a result of accumulation of the radiometal would result in extremely high toxicity. These combinations are clearly unsuitable for RIT. Cumulative dose of 90Y-TFM to the kidney was 3 times lower than the divalent forms but still twice as high as for 90Y-IgG. TFM clears faster from the blood than IgG, producing higher tumour to blood ratios. Therefore when considering only the tumour to blood ratios of the total absorbed dose, the data suggests that TFM would be the most suitable candidate. However, when corrected for equitoxic blood levels, doses to normal tissues for TFM were approximately twice the level of IgG, producing a two-fold increase in the overall tumour to normal tissue ratio. In addition RIT revealed that for a similar level of toxicity and half the administered activity, 90Y-IgG produced a greater therapeutic response. This suggests that the most promising A5B7 antibody form with the radionuclide 90Y may be IgG. Dosimetry analysis revealed that the tumour to normal tissue ratios were greater for all 131I-labelled antibodies. This suggests that 131I may be a more suitable radionuclide for RIT, in terms of lower toxicity to normal tissues. The highest tumour to blood dose and tumour to normal tissue ratio at equitoxic blood levels was 131I-labelled DFM, suggesting that 131I-DFM may be best combination of antibody and radionuclide for A5B7. The dosimetry estimates were in agreement with RIT results in that twice the activity of 131I-DFM must be administered to produce a similar therapeutic effect as 131I-TFM. The toxicity in this therapy experiment was minimal and further experiments at higher doses are required to observe if there would be any advantage of a higher initial dose rate for 131I-DFM. © 1999 Cancer Research Campaig

Gardens of happiness: Sir William Temple, temperance and China

This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this recordSir William Temple, an English statesman and humanist, wrote “Upon the Gardens of Epicurus” in 1685, taking a neo-epicurean approach to happiness and temperance. In accord with Pierre Gassendi’s epicureanism, “happiness” is characterised as freedom from disturbance and pain in mind and body, whereas “temperance” means following nature (Providence and one’s physiopsychological constitution). For Temple, cultivating fruit trees in his garden was analogous to the threefold cultivation of temperance as a virtue in the humoral body (as food), the mind (as freedom from the passions), and the bodyeconomic (as circulating goods) in order to attain happiness. A regimen that was supposed to cure the malaise of Restoration amidst a crisis of unbridled passions, this threefold cultivation of temperance underlines Temple’s reception of China and Confucianism wherein happiness and temperance are highlighted. Thus Temple’s “gardens of happiness” represent not only a reinterpretation of classical ideas, but also his dialogue with China.European CommissionLeverhulme Trus

The use of engineered E1A genes to transactivate the hCMV-MIE promoter in permanent CHO cell lines.

Vectors expressing adenovirus 5 E1A or a domain 2 mutant E1A were introduced into CHO-K1 cells in order to transactivate the hCMV-MIE promoter in transient and stable transfections. Expression from the hCMV promoter was efficiently activated by both wild-type and mutant E1A in contrast to other viral promoters such as the SV40 early promoter which are repressed by E1A. E1A genes expressed from a strong promoter were inhibitory to the growth of CHO cells. Nevertheless, by the use of a weaker promoter, it was possible to isolate stably transfected cell lines containing a level of E1A compatible with both continued cell growth and significant transactivation of the hCMV promoter. By this means we have generated cell lines secreting tissue inhibitor of metalloproteinases (TIMP) at levels approaching those previously attained using gene amplification. CHO cell lines constitutively expressing wild-type and mutant E1A genes have been derived which can serve as new host cell lines for transient expression and efficient stable expression without gene amplification